Manufacture of paper



?atente d may id, 1935 2 2&91346 MANUFAQTEIRE @E" PAPER omn 1r. de sert, lvfiamisburg, oalc, assignor to Howard ll. liileinche.

No Drawing. Uriginal application March 5, 1931,

Serial No. 520,481. Divided and this applicathan July 13, 1932, Serial No. 622.3%

5 Claims. (@l. W -21) The present invention relates to improvements ingredients employed. Likewise, similar proporin connection with the manufacture of paper and 610115 y be incorporated in the Case Of laymore particularly to improvements in the menu in the case of calcium carbonate, alum only need facture and incorporation of fillers. be added. (in account of the fact that part of 5 The methods which have heretofore been made the calcium carbonate reacts with the alum, 5

to utilize clay, calcium carbonate or calcium sul- Slightly less elllm Should be added them With the fate (either in its natural crystalline form as gype 8 p Sum, 01' after partial or complete calcining) as Instead of lime, other alkalies may be added, a filler or as a coating medium in connection with such as sodium, potassium or ammonium hy- 10 the manufacture of paper, the dimcultiss in disdr x d wis the a u nu hyd a may w persion or" the filling or coating material, lack of be separately prepared and directly incorporated ention by the pulp or fiber and lack of coatin the mix u ing power have afiorded serious dlfilculties, not= When the mixture is incorp in W a withstandmg the marked advantages of the mamarkedly mproved disper i and p n n l5 terials by reason of their low cost and whiteness. of the time Of settling of the filling material is 115 It has now been discovered that the efiect oi noted. When the suspension thus produced is these materials as fillers or coating materials may incorporated in P p P p in a suitable mixer be markedly changed by the procedure hereinor beater, it is found that the retention of the after described. filling material is markedly increased.

so In accordance with this invention, a relatively The fi i al ay e incorporated wi small proportion of a readily suspensible colloid t e p p p p either in the beater, in the Stllfi such as aluminum hydrate is admixed with the Chest. p the Felll'dliniel Screenclay, gypsum or calcium carbonate. It is pre- 0n incorporation of suitable casein or starch ferred to accomplish this result by the addition sizes with a filler prepared in accordance with of small proportions of alum with an alkaline lime the present invention, the resulting material may 25 p d Such as lime, calcium carbonate or hybe used as a coating material or surface size in drated lime. Obviously, in the case of the calthe p epa n of p pe a w b found to cium carbonate it is not necessary to add lime, the av e markedly increased hiding power and addition of alum being sumcient. The proportion the whiteness of the coated pap W be ly of the soluble aluminum compound is in general p v 30 less than 10% of the amount of the filler, and the This app i a i i a division of y co-pendi s proportion of the alkaline lime compound is so application Serial No. 520,481, filed March 5, 1931. controlled that when the composite product is The foregoin il descriptiell has been incorporated in water, a resulting solution will given for cle m s of under t ndin nly, and

have a pH suitable for the process in widen the no unnecessary limitations should be understood 35 filler is to be used. In general in paper making, therefrom, but the appended claims should be it is desired to have the solution either approxiconstrued as broadly as permissible, in view of the mately neutral or slightly acid. The proportion prior art. of the alum may in general be from 5-35 parts I claim:

lo by weight for each 100 parts of the filler, and the 1. In the preparation of paper, the method of 40 proportion of the lime compound from 1-15 parts incorporating calcium sulfates therein, which by weight. A typical preparation in accordance comprises incorporating in the paper pulp a diswith the present invention may be prepared by persion of calcium sulfate containing small proadmixing thoroughly with 100 parts of finely portions of a soluble aluminum compound and as ground natural gypsum, 8 parts by weight ofan alkaline lime compound. alum, and 2.5 parts by weight of hydrated lime. 2. In the manufacture of paper, the method of The ingredients may be mixed dry, the mixture incorporating calcium sulfate therein which com being subsequently incorporated in water, al prises introducing into the paper pulp a though it is preferred to pro-mix the materials sion oi calcium sulfate containing small proporwhile moist and permit them to dry at a temperations of an alum and hydrated lime. 50 ture below that at which the colloidal efiect of the 3. The method of improving the filler in pap aluminum hydrate is adversely aiiected. Either pulp which comprises incorporating with calcium the partially or completely calcined gypsum may sulfate small amounts of a soluble aluminum combe substituted for the natural gypsum without pound and an alkaline lime compound, thereby se substantial modification of the proportion of the increasing the dispersibility of the calcium sul- 2 fate, and then adding the above described mixture to paper pulp.

4. In the manufacture of paper, a method of incorporating calcium sulfate therein which comprises introducing into the paper pulp a dispersion of calcium sulfate containing 5-35 parts of alum and 1-15 parts of lime for each 100 parts of calcium sulfate.

5. In the manufacture of paper, a method of incorporating calcium sulphate therein which comprises introducing into the raw paper pulp 100 parts of finely ground natural gypsum, approximately 8 parts by weight of alum, and approximately 2.5 parts by weight or hydrated lime. 5

oavon P. GEDPHART. 

